The analysis of urine samples is widely used to assess the internal contamination of radionuclides from the amount excreted as a function of the time after intake. For contamination by actinides, these analyses are commonly performed using alpha spectrometry. However, in this case, in addition to the time required for the sample purification, a long counting time is generally necessary to reach the low detection limits required. Nowadays, in order to improve such analyses, the use of mass spectrometry techniques is being tested. The use of Secondary Ion Mass Spectrometry (SIMS) has been investigated to measure trace amounts of long-lived alpha emitters. This report aims to assess the range of applicability of SIMS (isotopic ratio measurement and detection limits) as an analytical tool for urine samples contaminated with low concentrations of uranium.